Hi all,

I am about finished with reassembling my air conditioner system for my 1999 with the Auto HVAC and have a question regarding adding oil to the system.

I'm afraid I spilled some of the oil out of the old compressor so using the amount that was in it as a reference is not an option. However I have replaced and flushed the rest of the system so I think I'm in the situation of starting from scratch with regard to adding refrigerant and the oil.

Here is what has been installed and/or flushed

Evaporator: original now flushed
Condenser: replaced
Accumulator: replaced
AC lines (3): original now flushed
Compressor: new

The GM manual says that the total oil charge for the system is 8 oz but does not say into what component the oil should be put: i.e. all in the compressor? Or some in allow in the accumulator?

The instructions for the new compressor (GPD pn 6512124 from Rock Auto) say that 60% of the total oil should be in the compressor and that if the accumulator is replaced to add 2 oz and if the condenser is replaced to add 3 oz more. It does not say where to add this oil.

The Chilton manual says that if that if any of these have been replaced, then to add the corresponding amount of oil to each:
accumulator, 2 oz;
condenser, 1 oz;
evaporator, 1 oz.

Finally, the instructions that came with my compressor say that the correct amount of oil for the compressor is on the label on its side. The label reads 190 ml (= 6.4 oz). (Note: 6.4 oz = 80% of the GM manual total oil amount of 8.0 oz for the OEM HT6 style compressor)

So to summarize: For an AC system that has has new parts and has been thoroughly flushed, what is the total amount of oil that should added and into what parts should it be put?

Total = 8.0 oz?
How much in compressor and how much to add elsewhere?

 

If I was in a hurry and had to I'd put 6 oz. in the compressor and 2 oz. in the accumulator to keep the manual and the label on the compressor withing spec. Since you flushed some of the parts you'll need to hold it under vacuum longer to boil that off. That gives us time for research.

 

I replaced my condenser yesterday so today the compressor clutch started making noise. I'm not replacing the clutch to have the compressor blow and contaminate the whole system. Getting ready to replace the same parts you have. I'm studying Captain Hook's posts after I read the manual but before I do anything.

 

I stopped for the day because while doing research on how much oil to put in, I came across a note from the compressor manufacturer that AC lines with mufflers (that wider can in-line with the hose near the compressor) cannot be flushed. Having found LOTs of black crud at the orifice filter, I know there there was crud throughout the system and thus it was appropriate to get a new hose. (Tech Tip #28 - global parts distributors, llc)

So I rush ordered the proper part and will have a couple days to figure out the answer to my original question. I also sent an email to GPD asking them the same. I'll report back what I learn.

P.S. Having found that crud, I was glad to have also replaced the condenser. But boy what a hassle that was. Ugh. I guess I should not be surprised as these Blazers are not the largest vehicles.

 

How do you flush an AC system?

 

This video explains it pretty well.
So to elaborate, any component with a cavity that is not "simply" connected to the rest of the system so that fluid can flow cannot be flushed. This includes the condenser because the passage ways are too small, the compressor because of the pistons, the orifice tube because of its built-in filter and small orifice, the accumulator because it has two pipes that both go into a larger cavity that so that liquid cannot always come back out, and any line that has a muffler because these have baffles.

For our Blazers, this pretty much leaves only the evaporator tube (the one that goes to the bottom of the evaporator and the evaporator itself as the only two components that can be flushed on our systems.

I used about 2 quarts of the flushing fluid to be certain I had the evaporator cleaned out. In retrospect I might have been able to get away with 1 qt as some of the discoloration I had in the fluid after it came out was probably from interacting with the inside of the old heater hose I had used to direct the fluid out of the bottom of the evaporator to a clean bucket under the truck instead of being due to contamination in the evaporator.

I know I must had crud in the system as the orifice tube was plugged.

 

Be sure to stick with the same oil type and viscosity that came with the replacement compressor.

 

I ordered the same GPD #9612779 sanden style compressor kit from rockauto. I also ordered the acdelco optional automatic adjusting orifice tube #1550120. Had I not been able to find one made by ac delco I may have just used the fixed orifice from the kit. Regular shipping I'll have it end of this week. From what I read the compressor comes filled with oil but I'll know for sure when it arrives.

 

When you pull vacuum on an AC system, how does that not pull the oil out?

 

Basically, the fixed oil does not evaporate.